1. Field of the Invention
The present invention generally relates to electrical auxiliary equipment for vehicles. More particularly, the invention relates to electrical auxiliary equipment for vehicles of the type which has a trouble point self-diagnostic function.
2. Description of Relevant Art
In general, vehicles have mounted thereon various electrically controlled auxiliary equipment such as an air conditioner. Some of such auxiliary equipment is constituted in a complicated manner with many electrical and mechanical elements, including an operation mode indicator therefor, and require accuracy in operation.
In order that complex auxiliary equipment operates normally, various measures are provided for detecting the early stages of abnormal operation of components.
For example, according to a conventional measure, for auxiliary equipment mounted on a vehicle, an exclusive external apparatus, such as a tester separated from the equipment, is provided to be connected thereto in order to diagnose any trouble with the equipment. Moreover, in another conventional measure, auxiliary equipment for vehicles has a self-diagnostic function internally.
In the former measure, the diagnosis of an equipment problem requires disassembly as well as reassembly of the entirety thereof or at least checks of respective components thereof. Thus, professional skills are needed so that it is considerably hard for a driver of a vehicle to diagnose equipment problems. In this respect, the latter measure is better for maintenance purposes.
For vehicle-mounted auxiliary equipment with self-diagnostic functions, it is generally necessary to install on the rear face of a control unit of such equipment an exclusive switch which operates a self-diagnostic function, or to provide a select coupler in a place away from such a control unit.
The disposition of an exclusive switch or select coupler is inherently made at a place with limited access while the panel front of the control unit is operational, to avoid erroneous operations which otherwise might have accompanied the on-panel operation. If an exclusive switch or select coupler were installed on the panel front, careless operation of the switch by a driver may occasionally turn the auxiliary equipment from an operation mode to a trouble-diagnostic mode, thus confusing the driver.
In auxiliary equipment with such a switch or coupler, however, during problem diagnosis, the control unit has to be removed from the fixing point thereof, so that it takes a certain length of time. In addition, the provision of such a switch or coupler requires extra cost.
The present invention effectively solves such problems of control units of conventional electrical auxiliary equipment for vehicles of the type described.